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Old 13 October 2017, 09:50   #1
redblade
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256 Colours, Chunky Vs Planar, what was better?

I know the Amiga used Planar graphics, but for 256 colours, would chunky be the best format?

Planar, 40 bytes * 200 lines * 8 bitplanes = 64,000 bytes
Chunky, 1 bytes (from 00 - 256) * 320 pixels a line * 200 lines = 64,000 bytes.

It just seems like a lot of effort on a planar system having to go through every one of those 8 bitmaps to set the bit for a colour change? Trying to shift some sprites across seems like it would be a nightmare on a planar system. Is there any advantage of a 256 colour planar system?

Thanks
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Old 13 October 2017, 10:54   #2
alpine9000
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One advantage of an 8 bitplane planar system is you can have 2 independent 4 bitplane
playfields, which would be good for parallax scrolling and other similar effects.
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Old 13 October 2017, 11:11   #3
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Burst fetches and page fetches benefit chunky modes more. Likewise, narrow blits like the ones used in texture mapping favor chunky modes.

Planar modes are favored by a simpler GPU design and bitfield partitioning strategies. Among them are the ability to shade spread palettes algorithmically and the famous dual playfield mode, as mentioned.

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Old 13 October 2017, 14:24   #4
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Planar made sense initially because graphics performance was relatively low and planar made it easy to scale memory, DMA and performance. It was a good trade off of flexibility and a slightly awkward format.

When AGA was being designed they just wanted something quick, so they simply increased the number of available bitplanes and added 32 bit capability to support them. Even later the Akkiko chip was thrown in, but it was all just because unsufficient resources went to developing AAA with proper chunky modes.
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Old 14 October 2017, 15:23   #5
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Both chunky and planar modes have their own advantages. But there exists chunky to planar routines (c2p's), which converts a chunky screen held in fast ram to chip ram planar format. On a 68040/68060 its copyspeed, so this conversion does not slow down copy speed to chip ram. With Doom, you really see that planar format does not slow down faster Amigas. A 68030/50 MHz even outperforms a 386/40 MHz running Doom in benchmarks by a frame or two, despite doing the c2p. Also, a 68040 outperforms a 486 PC running Doom at same clockspeed. The chip ram access speed is more of a bottleneck on the Amigas, rather than the planar format.
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Old 19 November 2017, 16:28   #6
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We can only wish OCS had a chunky mode because then Doom and Wolf3d would have been possible on A500 with no need to C2p conversion. This would have allowed the Amiga to rule for even longer and provided Commodore the time and funds to finally make a next-gen Amiga
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Old 19 November 2017, 17:38   #7
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Doom (released December 1993) on A500? Uhm, no. But on A1200 (released October 1992) with 4 MB fast RAM, yes.
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Old 19 November 2017, 20:39   #8
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Doom running with (at best) 64 (EHB) colours vs 256 colours on the VGA PC? Yeah, right. Even with a chunky screen mode, that was never going to happen.
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Old 19 November 2017, 22:56   #9
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I think it's possible, cut floor and ceiling textures, no c2p conversion wasting cpu = playable doom
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Old 19 November 2017, 23:04   #10
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Quote:
Originally Posted by Miggy4eva View Post
I think it's possible, cut floor and ceiling textures, no c2p conversion wasting cpu = playable doom
Playable Wolfenstein maybe... with a 14 MHz accelerator to match the 20 MHz clock speed of a 286 running the same thing and at least 4 megabytes of fast RAM. Remember that the classic Mac version took 8 megabytes just for Wolfenstein, let alone Doom.
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Old 20 November 2017, 00:48   #11
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Quote:
Originally Posted by Dunny View Post
Doom running with (at best) 64 (EHB) colours vs 256 colours on the VGA PC? Yeah, right. Even with a chunky screen mode, that was never going to happen.
I've played Doom on a A3000 030/25 and 64 colors, wasn't that bad (I played it on a Pentium 90 in 1995-96 though). Must have been ADoom: http://aminet.net/package/game/shoot/ADoom-1.4
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Old 20 November 2017, 01:44   #12
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Quote:
Originally Posted by Miggy4eva View Post
I think it's possible, cut floor and ceiling textures, no c2p conversion wasting cpu = playable doom
Well yes, but with no c2p conversion you're looking at a black screen.
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Old 20 November 2017, 02:14   #13
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The irony is, if the Amiga designers had designed the copper chip to be able to reload the colour registers every 1 pixel instead of the 8 it could do.....theres your chunky mode right there in 1985!
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Old 20 November 2017, 02:47   #14
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Quote:
Originally Posted by Dunny View Post
Well yes, but with no c2p conversion you're looking at a black screen.

Comprehension fail
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Old 20 November 2017, 05:44   #15
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The classic Mac 2 had chunky modes and colors. 16 colors. The A500 wouldn't have had 8bit color in 1987 even with chunky modes.
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Old 20 November 2017, 11:39   #16
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Quote:
Originally Posted by Miggy4eva View Post

Comprehension fail
Well, how else were you going to get the display up on the screen? You have to go from textured polys to screen display and that requires a chunky to planar conversion. That's kinda the whole point of these kinds of thing.
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Old 20 November 2017, 12:32   #17
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Quote:
Originally Posted by Dunny View Post
Well, how else were you going to get the display up on the screen? You have to go from textured polys to screen display and that requires a chunky to planar conversion. That's kinda the whole point of these kinds of thing.
I was talking about if OCS had a chunky mode.
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Old 20 November 2017, 14:55   #18
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Play Doom on an A4000 with graphics card (no c2p involved). Still not fast.
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Old 20 November 2017, 16:50   #19
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Quote:
Originally Posted by Miggy4eva View Post
I was talking about if OCS had a chunky mode.
I don't think you quite understand how these things work. If the A1000/A500 had a chunky mode then memory requirements would have been much, much higher - one of the main reasons we got planar was due to the smaller display footprint. And back in the 80s, RAM was expensive.

Besides, the A500 didn't have a chunky display so the whole discussion is moot. Graphically speaking, the Amiga was vastly inferior to a PC that could natively run Doom.
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Old 20 November 2017, 17:03   #20
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Quote:
Originally Posted by Dunny View Post
I don't think you quite understand how these things work. If the A1000/A500 had a chunky mode then memory requirements would have been much, much higher - one of the main reasons we got planar was due to the smaller display footprint. And back in the 80s, RAM was expensive.
If it had a chunky mode it doesn't mean you have to use it all the time. It's just one mode available.

Quote:
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Besides, the A500 didn't have a chunky display so the whole discussion is moot. Graphically speaking, the Amiga was vastly inferior to a PC that could natively run Doom.
OMFG, is it just me or do we have a major wire crossed here? This is the sequence of comments we exchanged, please tell me where I lost you

It all started when I made this first comment:
Quote:
Originally Posted by Miggy4eva View Post
We can only wish OCS had a chunky mode because then Doom and Wolf3d would have been possible on A500 with no need to C2p conversion. This would have allowed the Amiga to rule for even longer and provided Commodore the time and funds to finally make a next-gen Amiga
Quote:
Originally Posted by Dunny View Post
Doom running with (at best) 64 (EHB) colours vs 256 colours on the VGA PC? Yeah, right. Even with a chunky screen mode, that was never going to happen.
Quote:
Originally Posted by Miggy4eva View Post
I think it's possible, cut floor and ceiling textures, no c2p conversion wasting cpu = playable doom
Quote:
Originally Posted by Dunny View Post
Well yes, but with no c2p conversion you're looking at a black screen.
This is where you seemed to forget the context of this whole discussion, which was my first comment saying I wish Amiga had a chunky mode

Quote:
Originally Posted by Miggy4eva View Post

Comprehension fail
Quote:
Originally Posted by Dunny View Post
Well, how else were you going to get the display up on the screen? You have to go from textured polys to screen display and that requires a chunky to planar conversion. That's kinda the whole point of these kinds of thing.
Quote:
Originally Posted by Miggy4eva View Post
I was talking about if OCS had a chunky mode.

And then after this you say it's a moot point? It's the point of this thread.
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